This invention relates generally to optical systems, and more particularly, to optical switching and routing systems which incorporate controllable, switchable mirrors therein.
With the advent of substantial new uses for high bandwidth digital and analog electro-optic systems, there exists a greater need to effectively control the route of electro-optic or optical signals from among many possible paths. This is especially true in digital computing systems where signals must be routed among processors, in analog systems such as phased array radar, and in the switching of high bandwidth optical carriers in communication systems. However, it should be realized that these are just several of numerous electro-optic systems which require the use of an optical switching or routing mechanism.
In many current and future systems light beams are modulated in a digital and/or analog fashion and are used as xe2x80x9coptical carriersxe2x80x9d of information. There are many reasons why light beams or optical carriers are preferred in these applications. For example, as the data rate required of such channels increases, the high optical frequencies provide a tremendous improvement in available bandwidth over conventional electrical channels such as formed by wires and coaxial cables. In addition, the energy required to drive and carry high bandwidth signals can be reduced at optical frequencies. Further, optical channels, even those propagating in free space (without waveguides such as optical fibers) can be packed closely and even intersect in space with greatly reduced crosstalk between channels. Finally, operations that are difficult to perform in the lower (e.g., radio) frequencies such as time shifting for phased array applications can often be performed more efficiently and compactly using optical carriers.
A common problem encountered in applications in which high data rate information is modulated on optical carrier beams is the switching of the optical carriers from among an array of channels. These differing optical channels may represent, for example, routes to different processors, receiver locations, or antenna element modules. One approach to accomplish this switching is to extract the information from the optical carrier, use conventional electronic switches, and then re-modulate the optical carrier in the desired channel. However from noise, space, and cost perspectives it is more desirable to directly switch the route of the optical carrier from the input channel to the desired channel.
Another common problem arises in applications where there is a need to arbitrarily interconnect any of n electronic input channels to any of n output channels. This xe2x80x9ccrossbar switchxe2x80x9d type of function is difficult to implement electronically. In such a case better performance may be obtained by modulating the electronic information on optical carriers, and switching the optical carriers to the desired channel where they may be reconverted to electronic information if desired.
Still another problem that is typical in switching systems is the insertion loss they impose. Some switching systems divide the input signal power into many parts, and block (absorb) the ones that are not desired. Others use switches that are inefficient and absorb or divert a significant part of the input signal.
It is therefore an object of this invention to provide an optical system that can independently route the optical carriers from an array of input channels to selected members of an array of output channels.
It is another object of this invention to provide an optical system that can independently route the optical carriers from an array of input channels to selected members of an array of output channels including the capability to switch one input channel to more than one output channel if desired.
It is also an object of this invention to provide an optical system that provides for a reduced complexity in terms of number of required optical switching elements and control points when compared with many other optical switches.
It is a further object of this invention to provide an optical system that relies upon a series of uniquely designed switching components.
It is a further object of this invention to provide an optical system that uses switchable mirrors to route or switch multiple wavelength optical signals, such as wavelength division multiplexed digital telecommunication signals, to selected output locations.
It is a still further object of this invention to provide optical systems that provide variable optical attenuation of input optical signals.
It is a further object of this invention to provide optical systems that provide polarization independent switching and attenuation of optical signals.
It is an even further object of this invention to provide optical systems that can selectively polarize an input unpolarized optical beam or signal under electronic control.
The objects set forth above as well as further and other objects and advantages of the present invention are achieved by the embodiments of the invention described hereinbelow.
More specifically, the present invention overcomes problems associated with sensitivity to the wavelength of the optical carriers, insertion loss, number of required switching devices and control signals, switch isolation, noise and crosstalk suppression, spurious reflections, data skew, and compactness that are present in other optical switching, routing, interconnection, and time delay systems. The present invention includes devices that use high efficiency switched mirrors to form optical switching, interconnection, routing, variable optical attenuation, polarizing systems, and time delay networks.
Furthermore, the switched mirrors can function, for example, by diffraction (diffractive mirrors) or reflection (reflective mirrors) and have the benefits of a lack of dispersion, where the steered direction does not strongly depend on wavelength. This added benefit can be an asset in very high bandwidth and wavelength multiplexed systems.
In addition, the present invention overcomes difficulties in obtaining uniform system performance on input optical signals or signal components that are orthogonally polarized.